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Re: Request for code review - (ZEE patch : Redundant Zero extension elimination)


On Fri, May 7, 2010 at 18:36, Diego Novillo <dnovillo@google.com> wrote:
> On 5/3/10 18:56 , Sriraman Tallam wrote:
>
>> +
>> +shr $0x5, %edx
>> +mov %edx, %edx --> Useless zero-extend.
>> +
>> +How to turn on ?
>> +----------------
>> +-fzee -O2
>> +
>> +*/
>
> Please indent this whole comment two spaces.

I think you meant three?

>> +fzee
>> +Common Report Var(flag_zee) Init(0)
>> +Eliminate redundant zero extensions on targets that supports implicit extensions.
>
> s/supports/support/
>
> What happens if the user specifies -fzee on a target that does not
> support implicit extensions?

The pass will simply not find any optimization opportunity.

Paolo


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